Radio communication devices typically employ antennas that optimize radio signal transmission and reception. The antennas are often coupled to the transmitter output signal and/or the receiver input signal connector though impedance matching circuits so that the transmitters and receivers can be designed and tested to a specified value. The impedance matching circuits can then be designed or adjusted for differing antennas or differing antenna environments, which vary the impedances of the antennas that may be coupled to the transmitters and/or receivers. Antenna matching circuits may have different impedance matching states that are selectable according to a radio channel and environmental conditions. In the case of handheld electronic devices, such environmental conditions include the presence of a user's hands in a variety of positions relative to an antenna or an antenna element.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of the embodiments.